build(deps): bump prost from 0.11.6 to 0.11.8 (#4405)

Bumps [prost](https://github.com/tokio-rs/prost) from 0.11.6 to 0.11.8.
- [Release notes](https://github.com/tokio-rs/prost/releases)
- [Commits](tokio-rs/prost@v0.11.6...v0.11.8)

---
updated-dependencies:
- dependency-name: prost
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -22,7 +22,7 @@ repository = "https://github.com/graphprotocol/graph-node"
 license = "MIT OR Apache-2.0"
 
 [workspace.dependencies]
-prost = "0.11.6"
+prost = "0.11.8"
 prost-types = "0.11.6"
 tonic = { version = "0.8.3", features = ["tls-roots", "gzip"] }
 tonic-build = { version = "0.8.4", features = ["prost"] }